1. Field of the Invention
This invention pertains to an improved oral appliance for improving breathing, reducing snoring and preventing apnea, and to methods of improving breathing and making an improved appliance.
2. The Prior Art
A significant fraction of the human pupulation has difficulty breathing when sleeping. The primary manifestations of breathing difficulties during sleep are snoring and sleep apnea.
Snoring is merely a symptom of a respiratory problem which manifests itself during sleep. These respiratory problems if left untreated, pose serious and even life-threatening risks.
The sound associated with snoring is produced when weak loose muscle tissues at the back of the mouth collapse into the pharyngeal airway, blocking normal breathing. Air must then be forced through the passage. That aggravating noise is created by vibrations of the soft muscle tissues as air is forced past them. Snoring is aggravating to family and friends and a cause of considerable interpersonal conflict. Professional and lay people alike realize that elimination of snoring is desirable.
Sleep apnea due to an obstructed airway, is a cause of serious disorders. Some of these disorders which have been frequently seen include daytime sleepiness, nocturnal insomnia, snoring as previously mentioned, abnormal motor activity during sleep, intellectual and personality changes, sexual impotence, morning headaches, systemic hypertension, pulmonary hypertension, COR pulmonale, heart failure, polycythemia, and unexplained nocturnal death.
There are several disorders associated with obstructive sleep apnea. These associative disorders include obesity, adenotonsillor hypertrophy or lymphoma, myxedema, micrognathia, goiter, myotonic dystrophy, temporomandibular joint disease and Shy-Drager syndrome.
Obstructive sleep apnea syndrome (OSAS) is receiving increasing attention as our understanding of these diseases broadens. OSAS is characterized by excessive daytime sleepiness and repeated episodes of upper airway obstruction during sleep.
The etiology of OSAS is unclear, but the sequence of events is established. In spite of normal central nervous system input and thoracic respiratory, effort, closure of the airway begins in the hypopharynx and oropharynx with inspiration. This causes airflow to cease, even though the larynx remains patent. The apneic period and the ensuing hypoxia are broken by cortical awakening and recruitment of accessory muscles. Thus, the person with OSAS will have many awakenings during the night and periods of decreased blood oxygenation.
The diagnosis of OSAS can be made by careful clinical history and overnight investigation in a sleep laboratory. Monitors applied to patients to record information while they sleep and in the morning, the paper recording is analyzed to correlate airway patency with sleep activity.
Treatment of OSAS is individualized, based on the severity of disease and physiological compromise.
Tracheostomy is universally successful, since the obstruction is supraglottic. Some patients experience apneas only when sleeping supine and may be treated with devices to encourage other sleep positions.
Drugs are of limited utility. Uvulopalatopharyngoplasty is successful in approximately 50 percent of people undergoing this procedure. The operation consists of removal of the uvula and redundant tissue in the pharynx. Air under continuous positive pressure may be delivered via a nasal mask during sleep to pneumatically splint the airway open.
The hallmark characteristics of people with OSAS are: overweight, sleepy, adult males.
Through many case reports, it is apparent that a group of people lacking the aforesaid age/sex/weight characteristics of OSAS have the disease. These people's common trait was a retrusive mandible.
The distance from the mandible to the hyoid bone and the diameter of the oropharyngeal airway shadow correlate to the presence of OSAS.
Mandibular lengthening procedures have been utilized in this group to attempt to increase airway diameter by repositioning the submandibular tissue forward. Procedures have included ramus osteotomies, costochondral grafts, and genioplasties. Series with successful utilization of various mandibular surgical procedures in patients with OSAS have been reported.
The night time use of splints to anteriorly reposition the mandible may serve as a predictor of success prior to mandibular advancement. Splints may also be utilized as an interim treatment prior to definitive surgery.
The diagnosis and treatment of OSAS is a field of emerging interest to a wide variety of professionals, including dentists.
Peter T. George in his U.S. Pat. No. 4,715,368 and DES302,036 has provided a discussion of OSAS and the prior art efforts on the subject. George provides an oral appliance that has rigid sockets for both the maxilla and mandible dental structure, a labial arch wire to engage the front superior dental arch, maxillary molar clasps and mandibular molar clasp. While George is silent in his specification as to mandibular advancement, it is obvious and apparent from examination of George's drawings that he has advanced the mandibular structure about one tooth because of George's mandibular clasp (11) being 1/2 tooth ahead of his maxillary clasp (5). The normal human has the mandibular molar about 1/2 tooth being or to the rear of the maxillary molar. The George device locks the mandibular and maxilla structures together.
Drs. Thomas E. Meade and Marvin B. Hays of the University of New Mexico have devised, tested and produced an oral appliance for the improvement of breathing during sleep and the prevention of snoring and obstructive apnea. Meade and Hays have sold this device under the trademark "Silent Night."
The Meade and Hays appliance is an integral one-piece device made of rigid cast acrylic and has a upper section which positively and rigidly fits upon the crowns of the upper or superior dental arch. The lower part of the device has a cam and a stop to engage the lower or inferior dental arch and extend the mandible forward to hold the throat airway open. The stop structure spaces the superior and inferior dental arches from each other and breathing apertures are provided.
The Meade and Hays appliance does provide prevention of snoring and obstructive apnea.
However, the Meade and Hays appliance is extremely painful to use. The problem is that the entire Meade and Hays appliance is precisely fitted to the upper crowns and is completely rigid. The force loadings applied by the appliance to the upper teeth are concentrated point loadings and the appliance tends to move the teeth of the user. This device will not conform to the user's dental geometry, so, usage is painful, keeps the user awake, and leaves the user with a very painful mouth in the morning.